a water level sensor 178 is illustrated. The water level sensor 178 operates using water in the heater tube assembly 120 (FIG. 9) to make a connection between a sensor element 180 mounted using an insulator 182 in a fitting 184 and the fitting 184 itself. A nut 186 is used to assemble the water level sensor 178, and a second nut 188 is used to connect a wire 190 onto sensor element 180. The fitting 184 of the water level sensor 178 screws into the boss 146 in the manifold 144 (FIG. 9).
The water level sensor 178 operates as a shutoff switch to automatically shut down the heating elements 158 in the heater tube assembly 120 if no water is sensed in the manifold 144. Under normal circumstances, water should always be in the heater tube assembly 120. The water level sensor 178 will thus only act as a safety device ,to prevent the heater tube assembly 120 from being heated in a dry state, thereby preventing the heating elements 158 from being operated dry and burned out.